This invention relates to wafer carriers. More particularly it relates to sealable wafer enclosures having doors with latching mechanisms.
Various methods have been utilized for enclosing wafers in containers for storage and shipping. Some containers have rigid bodies with vertical slots for receiving the wafers and have flexible snap-on covers. These containers are generally not suitable for use in applications where the wafers are not to be exposed to the ambient atmosphere.
For wafers in the range of 200 mm and smaller, containers known as SMIF (standardized mechanical interface) pods 20 such as shown in FIG. 1, have been utilized to provide a clean sealed mini-environment that allows transfer of wafers into processing equipment without exposing the wafers to the ambient atmosphere. Examples of these pods are shown in U.S. Pat. Nos. 4,532,970 and 4,534,389. Such SMIF pods typically utilize a transparent container portion 34 with a lower door frame portion 35 configured as a flange defining an open bottom and a latchable door 36 that closes the open bottom. The door frame portion 35 clamps onto processing equipment and a door on the processing equipment attaches to the lower SMIF pod door. Both doors may be simultaneously lowered downwardly from the shell into a sealed processing environment in said processing equipment. A separate H-bar carrier 38 positioned on the top surface 40 of the SMIF pod door 36 and loaded with wafers is lowered with the pod door for accessing and processing said wafers.
The semiconductor processing industry is moving toward utilization of larger wafers, specifically 300 mm wafers. Transport modules for such wafers, by way of developing industry standards, are expected to utilize a front opening door for insertion and removal of the wafers as opposed to a bottom door that drops downwardly from the module. Referring to FIG. 2, such a front opening enclosure is shown. Such an enclosure has analogous components to the SMIF pod although the wafers may be supported within the container portion 34 without a separate removable carrier.
Various configurations of door enclosures and latching mechanisms for sealable enclosures are known in the art. Generally, these have the disadvantage that they are not easily disassembled, they have numerous moving parts, and they utilize metallic parts including fasteners. The use of metallic fasteners or other metal parts is highly undesirable in semiconductor wafer carriers or containers. Metallic parts generate highly damaging particulates when rubbed or scrapped. Assembly of a module with fasteners causes such rubbing and scrapping. Thus, the use of metal fasteners or other metal parts in wafer enclosures is to be avoided.
Latching mechanisms known in the art will often use rotatable cammed members. These cammed members have typically been formed of planar plastic plates with elongate recesses defining cam surfaces. These cam surfaces only provided motion of the cam follower in one direction, typically a single back and forth radial direction that translated to an extension and retraction of the latching portions. Other means, which typically added substantially component parts, were necessary for providing a motion of the latching portions in a direction away and towards the container portion for securing and sealing the door. Such additional component parts increase manufacturing costs, increase the complexity of the latching mechanism, increase the difficulty in assembly and disassembly, and increase the number of rubbing and scrapping surfaces which generate more particulates.
Although enclosures as described above are utilized in relatively clean environments, such enclosures will over time accumulate contaminants on and in the enclosure and in the interior of the door enclosure ultimately requiring cleaning. Such contaminants may be created by rubbing of parts such as the operation of the door latching mechanism as described above, by the wafers being loaded and unloaded on the wafer shelves, and by the door being engaged and disengaged with the container portion. The numerous parts in conventional latching mechanisms, the difficulty of disassembly of the doors, and the use of metallic fasteners make the cleaning of such doors difficult. An easily disassembleable door, with an easily disassembleable latching mechanism, and with minimal moving parts is needed.
The door with the features as disclosed and claimed herein are suitable for use with either of the type of enclosure as described above and satisfy the needs as described.